Brake drum



March 13, 1956 H. J. HORN ETAL BRAKE DRUM Filed June 21, 1949 FIG 4 III IIIII FIG; 6

INVENTOR. HARRY J. y& JOSEPH A. WATSON I HORN FIG. 5

United States Paten c r 2,738,038 BRAKE DRUM Application June 21, 1949, Serial No. 100,353

Claims. (Cl. 188-218) This invention relates to a brake drum.

It is old in the art to make a brake drum by centrifugally casting an iron lining in a preformed cylindrical shell or ring of low carbon steel, see, for example, the Campbell Patents 2,085,726 and 2,085,727. Such centrifugally cast iron brake drums with reinforcing steel rings have gone into extensive commercial use. In the casting of such drums, as pointed out in the Campbell patents, the steel shell or brake ring is heated to a temperature between 1200" and 1500" F. in order to efiect a good bond with the molten iron lining which is cast at a temperature between 2700 and 3000 F. Thus, to avoid distortion in the brake drum back it has been customary in all such centrifugally cast iron brake drums (1) to form the steel back and ring separately and, then subsequent to the casting operation, attach the ring to the back by welding or riveting or (2) to form the steel back and ring integrally and, then subsequent to the centrifugal casting operation, to remove the distortion in the steel back (due to the high temperature (red heat) to which the integral back and ring are heated preparatory to the casting operation) by reforming the back in a press. Both of these methods of attaching the brake drum back to the ring require many operations each of which add to the expense of the finished brake drum.

It is an object of this invention to produce a centrifugally cast iron brake drum with a steel reinforcing ring with an improved mechanical attachment of the back to the brake ring and which is less expensive to produce.

Our invention also contemplates a new method of fabricating this type of brake drum which is more economical than the methods heretofore practiced and which is essentially characterized by simultaneously centrifugally casting the iron lining in the steel ring and in attach ing the drum back to the lining and ring.

We have found that if the steel brake back is made separate from the steel ring and the edge portion only of the steel back is embedded in the centrifugally cast iron lining that it is not necessary to heat the brake back to effect a good connection between the cast iron lining and brake back and that a good union or connection between the back and the lining can be effected when the back is at substantially room or atmospheric temperatureat the time the molten iron is cast thereabout.

In the drawing:

Fig. 1 is an elevation looking at the back of our brake drum.

Fig. 2 is a cross section taken on the line 2-2 of Fig. 1.

Fig. 3 is a section taken on the line 33 of Fig. 1.

Fig. 4 is a section taken on the line 4-4 of Fig. 1.

Fig. 5 is a fragmentary elevation looking at the back of a modified form of our drum.

Fig. 6 is a section taken along the line 6-6 of Fig. 5.

Referring more particularly to the drawing our brake drum comprises a steel ring 1 provided with circumferential flanges 2 and 3, a steel back 4 and a centrifugally cast iron lining 5. Circumferential flange 3 initially extends in an axial direction as illustrated in Fig. 2. Before 2,738,038 Patented Mar. 13, 1956 casting the lining 5 in ring 1, back 4 is placed in ring 1 and centered on theradially extending flange 2 by means of the sheared out-embossments 6 which are three in number. After back 4 has been placed in ring 1 in the position shown in Fig. 2, then flange 3 is bent radially inwardly so as to cooperate with flange 2 and form a channel into which the iron lining 5 is centrifugally cast.

The casting of lining 5 is effected according to the method set forth in the above-mentioned Campbell patents except that back 4 is not heated, back 4 at the beginning of the casting operation being substantially at room or atmospheric temperature. If ring 1 is heated in an induction heater with back 4 in position and before the casting operation, then the circumferential edge portion only of the back may be raised above atmospheric temperature but this is not essential to obtain a good connection between back 4 and lining 5. However, due to the small circumferential area, generally designated 7, of back 4 which is embedded in, and in heat conducting relation with, lining 5, this peripheral area 7 during the casting operation is heated by conduction from the hot cast iron lining 5 to a temperature sufliciently high to effect a strong connection or union with lining 5 but not necessarily of the same order as is effected between lining 5 and steel ring 1. The steel ring 1, of course, is heated to a temperature in the neighborhood of between 1200 and 1500 F.

The peripheral portion 7 of the back 4 is sheared radially inwardly a short distance from the circumference of back 4 at a plurality of places as at 8 and the tabs 9 between alternate pairs of shears are bent axially to the left, Fig. 3, or toward the open end of the finished brake drum. The main peripheral portion 7 of the back 4 lies against the flange 2. Thus, it will be seen that the cast iron lining 5 not only forms a liningfor the steel ring 1 but at the same time flows around tabs 9' and the circumferential edge 7 of back 4 and securely fastens the back to the ring. After the casting operation flange 3 at the open end of the drum is machined away.

In the modified form shown in Figs. 5 and 6 the brake drum and the method of making the same is identical with our principal form of brake drum, Figs. 1 to 4, except that tabs 10 (corresponding to tabs 9) in the circumferential edge portion 7 of back 4 are bent to the right or toward the closed end of the brake drum. Since the tabs 10 extend to the right, they will contact the flange 2 and hold back 4 away from flange 2.

When the iron lining 5 is centrifugally cast into the ring 1 it will not only line the ring 1 but will also flow and completely surround the circumferential edge portion 7 including tabs 10 of the back 4. Here again the flange 3 will be removed by machining after the casting operation is completed.

From the above it will be seen that our method produces a centrifugally cast iron type of brake drum with a minimum number of steps which greatly reduce the cost of production of these drums and the finished drum has not only all of the high strength and other advantages of the centrifugally cast iron type of drum with a steel reinforcing ring but also has a greately improved mechanical attachment of the back to the brake ring.

The back 4 and the ring 1 will be formed of low carbon steel and since the iron lining 5 will be cast at a temperature falling within a range between 2700 F. and 3000 F., a fusion bond will be obtained between the lining 5 and the inner face of ring 1 and may be obtained between lining 5 and the circumferential edge portion 7 of the back 4.

We claim:

1. A composite brake drum comprising a sheet steel brake ring having an integral radially inwardly extending circumferential flange, a sheet steel drum back fitted .3 within said ring, the circumferential edge portion of said drum back being provided with a plurality of radially "extending tabs, there being a clearance between the adjacent radial edges of adjacent tabs, at least some of said tabs contacting the inner face of said circumferential flange to position said drum back axially relative to said brake ring and a centrifugally cast iron lining fused to the inner face of said ring, said tabs being embedded "in said lining to secure the drum back "and brake "ring together.

2. A brake drum as claimed in claim 1 wherein some of said tabs are bent axially so that a portion of said tabs are axially offset from others of said tabs.

3. A brake drum as claimed in claim 1 wherein-apertion of said tabs are bent axially towards the open end of said drum and "the remaining tabs are in co-pl'anar engagement with the inner face of said circumferential flange on said "brake ring.

4.,A brake drum as claimed in claim 1 wherein said iron lining is fused to said tabs.

4 5. A brake drum as claimed in claim 1 wherein a portion of said tabs are bent axially towards the closed end of said drum, said last mentioned tabs contacting the inner face of said circumferential flange and the remaining tabs being spaced axially from said flange.

References Cited :in the file of this patent UNITED STATES PATENTS 2,008,173 Dakeiet al July 16, 1935 2,014,865 Schmidt Sept. 17, v1935 2,035,142 Campbell Mar. 24., 19.36 2,041,776 Nelson May 26, 1936 2,107,229 Ash Feb. -1, 1938 2,112,697 Van Halteren Mar. 29, 1938 2,127,597 Horn Aug. 23, 1938 2,294,466 Lejeune Sept. 1, 1942 2,471,661 Stevenson May 31, 1949 2,623,254 Proctor Dec. 30, 1952 

